package java.security.cert;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;

import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.DERInputStream;
import org.bouncycastle.asn1.DERObject;
import org.bouncycastle.asn1.DERObjectIdentifier;
import org.bouncycastle.asn1.DEROutputStream;
import org.bouncycastle.asn1.util.ASN1Dump;

/**
 * An immutable policy qualifier represented by the ASN.1 PolicyQualifierInfo 
 * structure.<br />
 * <br />
 * The ASN.1 definition is as follows:<br />
 * <br /><pre>
 *   PolicyQualifierInfo ::= SEQUENCE {
 *        policyQualifierId       PolicyQualifierId,
 *        qualifier               ANY DEFINED BY policyQualifierId }
 * </pre><br />
 * <br />
 * A certificate policies extension, if present in an X.509 version 3 
 * certificate, contains a sequence of one or more policy information terms,
 * each of which consists of an object identifier (OID) and optional
 * qualifiers. In an end-entity certificate, these policy information terms
 * indicate the policy under which the certificate has been issued and the 
 * purposes for which the certificate may be used. In a CA certificate, these 
 * policy information terms limit the set of policies for certification paths 
 * which include this certificate.<br />
 * <br />
 * A <code>Set</code> of <code>PolicyQualifierInfo</code> objects are returned 
 * by the {@link PolicyNode#getPolicyQualifiers PolicyNode.getPolicyQualifiers} 
 * method. This allows applications with specific policy requirements to 
 * process and validate each policy qualifier. Applications that need to 
 * process policy qualifiers should explicitly set the 
 * <code>policyQualifiersRejected</code> flag to false (by calling the 
 * {@link PKIXParameters#setPolicyQualifiersRejected 
 * PKIXParameters.setPolicyQualifiersRejected} method) before validating 
 * a certification path.<br />
 * <br />
 * Note that the PKIX certification path validation algorithm specifies
 * that any policy qualifier in a certificate policies extension that is 
 * marked critical must be processed and validated. Otherwise the 
 * certification path must be rejected. If the 
 * <code>policyQualifiersRejected</code> flag is set to false, it is up to 
 * the application to validate all policy qualifiers in this manner in order 
 * to be PKIX compliant.<br />
 * <br />
 * <b>Concurrent Access</b><br />
 * <br />
 * All <code>PolicyQualifierInfo</code> objects must be immutable and
 * thread-safe. That is, multiple threads may concurrently invoke the
 * methods defined in this class on a single <code>PolicyQualifierInfo</code> 
 * object (or more than one) with no ill effects. Requiring 
 * <code>PolicyQualifierInfo</code> objects to be immutable and thread-safe 
 * allows them to be passed around to various pieces of code without 
 * worrying about coordinating access.<br />
 * <br />
 * Uses {@link org.bouncycastle.asn1.DERInputStream DERInputStream},
 * {@link org.bouncycastle.asn1.ASN1Sequence ASN1Sequence},
 * {@link org.bouncycastle.asn1.DERObjectIdentifier DERObjectIdentifier},
 * {@link org.bouncycastle.asn1.DEROutputStream DEROutputStream},
 * {@link org.bouncycastle.asn1.DERObject DERObject} and
 * {@link org.bouncycastle.asn1.util.ASN1Dump#_dumpAsString _dumpAsString}
 **/
public final class PolicyQualifierInfo
{
    private String id;
    private byte[] encoded;
    private byte[] qualifier;

	/**
	 * Creates an instance of <code>PolicyQualifierInfo</code> from the
	 * encoded bytes. The encoded byte array is copied on construction.<br />
	 * <br />
	 * Uses {@link org.bouncycastle.asn1.DERInputStream DERInputStream},
	 * {@link org.bouncycastle.asn1.ASN1Sequence ASN1Sequence},
	 * {@link org.bouncycastle.asn1.DERObjectIdentifier DERObjectIdentifier} and
	 * {@link org.bouncycastle.asn1.DEROutputStream DEROutputStream}
	 *
	 * @param encoded a byte array containing the qualifier in DER encoding
	 *
	 * @exception IOException thrown if the byte array does not represent a
	 * valid and parsable policy qualifier
	 */
    public PolicyQualifierInfo( byte[] encoded )
	throws IOException
    {
	this.encoded = (byte[])encoded.clone();
	try {
	    ByteArrayInputStream inStream = new ByteArrayInputStream(this.encoded);
	    DERInputStream derInStream = new DERInputStream(inStream);
	    ASN1Sequence obj = (ASN1Sequence)derInStream.readObject();
	    id = ( (DERObjectIdentifier)obj.getObjectAt(0) ).getId();
            ByteArrayOutputStream outStream = new ByteArrayOutputStream();
            DEROutputStream derOutStream = new DEROutputStream(outStream);

            derOutStream.writeObject(obj.getObjectAt(1));
            derOutStream.close();

            qualifier = outStream.toByteArray();
	} catch ( Exception ex ) {
	    throw new IOException( "parsing exception : " + ex.toString() );
	}
    }

	/**
	 * Returns the <code>policyQualifierId</code> field of this 
	 * <code>PolicyQualifierInfo</code>. The <code>policyQualifierId</code>
	 * is an Object Identifier (OID) represented by a set of nonnegative 
	 * integers separated by periods.
	 *
	 * @return the OID (never <code>null</code>)
	 */
    public String getPolicyQualifierId()
    {
	return id;
    }
   
	/**
	 * Returns the ASN.1 DER encoded form of this 
	 * <code>PolicyQualifierInfo</code>.
	 *
	 * @return the ASN.1 DER encoded bytes (never <code>null</code>).
	 * Note that a copy is returned, so the data is cloned each time 
	 * this method is called.
	 */
    public byte[] getEncoded()
    {
	return (byte[])encoded.clone();
    }

	/**
	 * Returns the ASN.1 DER encoded form of the <code>qualifier</code> 
	 * field of this <code>PolicyQualifierInfo</code>.
	 *
	 * @return the ASN.1 DER encoded bytes of the <code>qualifier</code>
	 * field. Note that a copy is returned, so the data is cloned each 
	 * time this method is called.
	 */
    public byte[] getPolicyQualifier()
    {
	if ( qualifier == null )
	    return null;

	return (byte[])qualifier.clone();
    }

	/**
	 * Return a printable representation of this 
	 * <code>PolicyQualifierInfo</code>.<br />
	 * <br />
	 * Uses {@link org.bouncycastle.asn1.DERInputStream DERInputStream},
	 * {@link org.bouncycastle.asn1.DERObject DERObject} and
	 * {@link org.bouncycastle.asn1.util.ASN1Dump#_dumpAsString _dumpAsString}
	 *
	 * @return a <code>String</code> describing the contents of this
	 *         <code>PolicyQualifierInfo</code>
	 */
    public String toString()
    {
	StringBuffer s = new StringBuffer();
	s.append("PolicyQualifierInfo: [\n");
	s.append("qualifierID: " + id + "\n");
	try {
	    ByteArrayInputStream inStream = new ByteArrayInputStream( qualifier );
	    DERInputStream derInStream = new DERInputStream( inStream );
	    DERObject derObject = derInStream.readObject();
	    s.append("  qualifier:\n" + ASN1Dump._dumpAsString("    ", derObject) + "\n");
	} catch ( IOException ex ) {
	    s.append(ex.getMessage());
	}
	s.append("qualifier: " + id + "\n");
	s.append("]");
	return s.toString();
    }
}
